This concerns a device for automatic bagging of lawn clippings, such as grass and/or leaves, in disposable bags such as the plastic lawn bags familiar to all. Since the invention is particularly useful as an attachment to a powered lawn mower, it will be described in such context. It will be recognized, however, that the invention may also be practiced in the form of a lawn sweeper with no mowing capability.
The advantages of a self-bagging lawn mower attachment have been recognized and numerous designs have been patented. These designs generally include a rigidly mounted bag holder around which the open end of a lawn bag is secured and a chute attached at one end to the discharge orifice from the lawn mower housing and at the other end to the bag holder. See for example U.S. Pat. Nos. 3,624,989; 3,722,192; 3,971,198 and 3,987,606. Many of these devices however are not commercially attractive since they do not provide an effective means of separating the air-entrained clippings from the air stream that blows the clippings through the chute and into the bag. The basic problem is that disposable lawn bags are made of impermeable plastic which requires air exhaustion to be made through the open top of the bag at the very point where the air-entrained clippings are being blown into the bag. This frequently results in clogging of the filter used to separate the clippings from the air stream. This is turn raises the back pressure in the bag, slowing down the air stream in the chute and reducing the collection efficiency of the lawn mower. As the air stream slows down, clippings are deposited in the chute and frequently the chute becomes clogged, causing the clippings to be scattered on the lawn.
The rigid mounting of the bag holder is another deficiency of previous designs. Rigid mountings tend to be heavy. Since the lawn bag is mounted behind the rear wheels of the mower, the weight of the mounting and the clippings in at least large bags tends to unbalance the mower, requiring a separate wheel or slide to support the bag. See, for example, U.S. Pat. Nos. 3,624,989 and 3,987,606. Such an arrangement is bulky and difficult to maneuver and its total weight is frequently unacceptable especially in lawn mowers that are not self-propelled. I have observed that a rigid bag mounting poses a further problem in that the bag often fills unevenly which has a tendency to strain the bag and sometimes tear it.